EARLINESS STUDY ON NEW EGYPTIAN COTTON GENOTYPES

This investigation was carried out to evaluate three genotypes of Egyptian cotton i.e., Giza 90, Giza 81 x Giza 83 and [(Giza 83 x (Giza 75 x 5844)] for early maturity using some earliness measurements during 2001 and 2002 seasons. Flowering data was collected daily, and the av­erage of flowers of 10 plants per week was calculated to construct weekly flowering curves, each genotype was picked weekly to calculate the percentage of crop harvested (PCH). Moreover, the other earliness measuremerts i.e. position of first fruiting node (PFN), days to the first flower (DFF), days to first boll opening (DFB), mean maturity date (MMD) and production rate index (PRI) were estimated. Simple correla­tion coefficients among five of the measurements and with seed cotton yield (SCY) were calculated to evaluate these methods. Rates of flowering followed a normal distribution curve, which was almost similar in all genotypes. The genotype (Giza 81 X Giza 83) pro­duced total number of flowers per plant more than any other genotype. Genotypes differences were significant in the 1^st, 4^th and 5^th weeks for (PCH). The highest (PCH) was found in fourth and fifth weeks. The geno­type (Giza 81 X Giza 83) was the earliest and produced 78.86% from the total of seed cotton yield in the first four picks. The combine of re­sults in the two crosses indicated insignificant differences at 1% level between all genotypes for all earliness measurements while the esti­mates of (PFN), (DFF) and (MMD) showed significant differences at 5% level between genotypes. Correlation coefficients results showed signifi­cant correlation between earliness measurements i.e. PFN, DFB, MMD and PRI with seed cotton yield (SCY).`